Self-study
P1
Scientists have long known that the soft surface of the bill of the platypus is perforated with openings that contain sensitive nerve endings. ████ █████████ ████████ ████ ██████████ █████████ ██ ███ █████ ██ ███ ████████ ████ ███ ██████ ████ ███ ████ ██ ██████ ███ ████ █████ ███████████ █ ██████████ █████████ ██ ███ ████ ████ ███ ████████ █████ █████ ███ ████████ ███ ██████ ████ ██ ██ ██████████ ███
Biologists' conclusion ·
Platypus uses its bill to locate prey underwater
We've known for a long time that the bill has nerve endings. Now biologists think those nerves on the bill are used for finding prey underwater.
New evidence supporting conclusion ·
Neurophysiological studies
Studies reveal two sensory receptors in pores on platypus bills: mechanoreceptors (respond to physical pressure), and electroreceptors (respond to electrical fields).
Bohringer's conclusion ·
Bill is the primary sensory organ for the platypus
This was supported by studies showing the bill is sensitive to touch.
Puzzle ·
How does platypus locate prey at a distance?
If a platypus isn't touching its prey with its bill, how can it find the prey? (Probably has to do with the electroreceptos, since we discussed the mechanoreceptors earlier.)
P2
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Set-up for Scheich's hypothesis ·
Platypus hunts by steadily wagging bill, then moving bill erratically after prey it finds prey
The erratic movements are called "searching behavior."
Scheich's hypothesis ·
Platypus distinguishes prey from non-prey by detecting electric fields
Scheich's experiment ·
Confirms platypus can detect electric fields
Platypus switches to searching behavior when it encounters electric field from battery. Then platypus attacked the battery like it was food.
Scheich's speculation ·
All invertebrates that platypus eats produce electric fields
We already know that shrimp prey of platypus produces an electric field.
Passage Style
Phenomenon-hypothesis (RC)
Single position
19.
Which one of the following ██████████ ██ ████ ███████ ██ █████████ ████████████ ████████ ██ ██ ██ █████████ ██ ███ ████████
Question Type
Analogy (RC)
To determine whether the platypus can sense prey using electroreception, Scheich used a battery to create an electric current in the water to see whether the platypus would swim toward the battery and treat it as prey.
a
To determine the ██████ ██████ ██ ██████ █ █████████ ██████ ██████ ████ ███ ██████ █████ ████ ████████ ███ █████ ███ ████ ████ ██████
This doesn’t involve an attempt to detect how birds sense something. In addition, the decoys are made to resemble the birds, which is part of what might influence the birds’ behavior. This isn’t analogous to Scheich’s experiment, in which the battery was not made to look like prey.
b
To determine whether ███████ ███████ ████ █████ ███ ██ █████████ ███ ██████ ██ █████ ██████ █ █████████ █████ █ ████ ██ ███ ████████ █████ ██ █████ █████████
This doesn’t involve an attempt to determine whether the animals can hear things. Rather, it’s an attempt to determine how it reacts to its own cries. This isn’t analogous, because Scheich wasn’t trying to figure out how the platypus reacts to something it produces itself.
c
To determine whether ██ ██████ ████ ████ ███████████ ██ ██████ █████ █ █████████ ██████ █ ███████████████ ██████ ████ ███ ████████ █████
This is the most analogous experiment. Just as Scheich used a battery that emits electric currents to determine whether the platypus detects prey by sensing electric fields, (C) involve use of an object that emits something (heat) to determine whether an animal detects prey by sensing the thing emitted.
d
A fisherman catches ████ ██ ████████ ██ ███ █████ ██████ ████████ ██ ███ ███████ ████ ████ ████ ████ ███████ ████ ████ ████
This doesn’t involve an attempt to determine whether fish can sense something emitted by an object. Rather, the object in this case looks like the fish’s prey, which is part of how the fish is attracted to the object.
e
A game warden ████████ ██ ██████ ██ ███████ █ ████ ████ █ █████ ██ ████ ████ ███ ██████ ████ ████ ██ ████
This doesn’t involve an attempt to determine whether the animal can sense something emitted by an object.